It seems twins have become a graduation ceremony staple this year alongside the caps and gowns.

At Central Middle School in Tinley Park, Illinois, the eighth grade class has nine sets of twins making up 7 percent of the total class, according to ABC News affiliate KTRK-TV. And at the tiny college of St. Norbert College in De Pere, Wisconsin, there are a reported eight sets of twins out of just 500 graduating seniors.

It might seem like there are more multiples than ever, but experts say we’re seeing the tail end of a medical trend that has already passed its peak.

Twin births steadily increased from 1980 to 2009 from 18.9 per 1,000 births to 33.2 per 1,000 births, according to the U.S. Centers for Disease Control. But the trend has leveled off since 2009, and has even shown signs of a decline in the years since. Births of three or more children have decreased 9 percent from 2011 to 2012.

Fertility clinics used to implant multiple embryos to boost the odds of a healthy pregnancy. But thanks to new techniques that check the health of an embryo before implantation, many are scaling back to the safer option of implanting a single embryo, according to Dr. Alan Copperman, the director of the Division of Reproductive Endocrinology and Infertility at Mount Sinai Hospital in New York.

“I think we’ll see a dramatic decrease over the next decade,” Copperman told ABC News of twin births. “[These older twins] will reflect blips in time with how we practiced medicine a decade ago…I’m thrilled for all of these healthy children graduating, [but] sometimes twin pregnancies don’t end well.”

Carrying twins or other multiples puts both mothers and infants at risk for dangerous complications, including premature birth. Dr. Joanne Stone, director of Maternal Fetal Medicine at Mount Sinai Hospital in New York, said her hospital has even seen an increase in women pregnant with multiples opting for selective reduction, a process that reduces the number of embryos in the womb to ensure a healthier pregnancy.

“There’s no doubt that multiple births are the main contributor to sickness or death regarding pregnancy,” said Stone. “We see people who have reduction to go from multiples to single birth – a recognition of [the risks or difficulty].”

But fertility treatments aren’t the only reason for the surge in twins. Stone said that women who get pregnant later in life are more likely to have multiples, and the rate of women aged between the ages of 40 and 44 who are having their first child doubled between 1990 and 2012, according to the CDC. But it’s unlikely that these spontaneous births will lead to another spike in twins or multiples similar to the spike from fertility drugs, Stone said.

As for this year’s graduating classes full of twins, Copperman said it serves as a reminder of the evolving effectiveness of fertility treatments.

"We’re looking at the effects of the trend today,” said Copperman, who said in the future people will be surprised by how many multiple births there were. “[In the future we’ll say,] ‘Do you remember in 2014 when everyone was a twin and now everyone has a single child?’”